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authorDenys Vlasenko <vda.linux@googlemail.com>2017-06-27 18:31:08 +0200
committerDenys Vlasenko <vda.linux@googlemail.com>2017-06-27 18:31:08 +0200
commit470bebe672fa179c89c0b04ee252ca564e8ee4d5 (patch)
tree54158444e31a478ad052d3cb12377f8671a2d323
parentf56ddf2e4ce42d7914d048f42fd952302027e8a3 (diff)
downloadbusybox-470bebe672fa179c89c0b04ee252ca564e8ee4d5.tar.gz
udhcpc6: add comments about option 39, no code changes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/udhcp/d6_common.h36
-rw-r--r--networking/udhcp/d6_dhcpc.c8
2 files changed, 42 insertions, 2 deletions
diff --git a/networking/udhcp/d6_common.h b/networking/udhcp/d6_common.h
index ca5788390..310550371 100644
--- a/networking/udhcp/d6_common.h
+++ b/networking/udhcp/d6_common.h
@@ -87,6 +87,42 @@ struct d6_option {
#define D6_OPT_IA_PD 25
#define D6_OPT_IAPREFIX 26
+/* RFC 4704 "The DHCPv6 Client FQDN Option"
+ * uint16 option-code OPTION_CLIENT_FQDN (39)
+ * uint16 option-len 1 + length of domain name
+ * uint8 flags
+ * char[] domain-name partial or fully qualified domain name
+ *
+ * Flags format is |MBZ|N|O|S|
+ * The "S" bit indicates whether the server SHOULD or SHOULD NOT perform
+ * the AAAA RR (FQDN-to-address) DNS updates. A client sets the bit to
+ * 0 to indicate that the server SHOULD NOT perform the updates and 1 to
+ * indicate that the server SHOULD perform the updates. The state of
+ * the bit in the reply from the server indicates the action to be taken
+ * by the server; if it is 1, the server has taken responsibility for
+ * AAAA RR updates for the FQDN.
+ * The "O" bit indicates whether the server has overridden the client's
+ * preference for the "S" bit. A client MUST set this bit to 0. A
+ * server MUST set this bit to 1 if the "S" bit in its reply to the
+ * client does not match the "S" bit received from the client.
+ * The "N" bit indicates whether the server SHOULD NOT perform any DNS
+ * updates. A client sets this bit to 0 to request that the server
+ * SHOULD perform updates (the PTR RR and possibly the AAAA RR based on
+ * the "S" bit) or to 1 to request that the server SHOULD NOT perform
+ * any DNS updates. A server sets the "N" bit to indicate whether the
+ * server SHALL (0) or SHALL NOT (1) perform DNS updates. If the "N"
+ * bit is 1, the "S" bit MUST be 0.
+ *
+ * If a client knows only part of its name, it MAY send a name that is not
+ * fully qualified, indicating that it knows part of the name but does not
+ * necessarily know the zone in which the name is to be embedded.
+ * To send a fully qualified domain name, the Domain Name field is set
+ * to the DNS-encoded domain name including the terminating zero-length
+ * label. To send a partial name, the Domain Name field is set to the
+ * DNS-encoded domain name without the terminating zero-length label.
+ * A client MAY also leave the Domain Name field empty if it desires the
+ * server to provide a name.
+ */
#define D6_OPT_CLIENT_FQDN 39
#define D6_OPT_TZ_POSIX 41
diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index 08a26fb57..ef9b9a5f2 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -98,8 +98,12 @@ static const char opt_req[] = {
static const char opt_fqdn_req[] = {
(D6_OPT_CLIENT_FQDN >> 8), (D6_OPT_CLIENT_FQDN & 0xff),
- 0, 2,
- 0, 0
+ 0, 2, /* optlen */
+ 0, /* flags: */
+ /* S=0: server SHOULD NOT perform AAAA RR updates */
+ /* O=0: client MUST set this bit to 0 */
+ /* N=0: server SHOULD perform updates (PTR RR only in our case, since S=0) */
+ 0 /* empty DNS-encoded name */
};
/*** Utility functions ***/